I must say, the only extractor I like/had great luck with is the spline type.. ie Snap-On..Ridgid sell them.
But order left hand drills and try them first..
At my shop, I always get them after everyone has buggered/gave up...on them
I have a set of Ridgid extractors I've had for years, the best I've used.
I'm a machinist by trade and I would get parts with broken e-z outs or drills or BOTH. The fastest way to get them out is chip them out with a sharp center punch.
My general rule of thumb; if the broken bolt can be moved then use the bolt extractor. If the bolt won't move, carefully centerpunch, then adjust the center with a center drill and drill motor. When you're satisfied the center is exactly in the center of the bolt, carefully drill a pilot hole ALL THE WAY THROUGH the bolt. Then drill with a tap drill, then remove the remaining bolt with a tap.
It's easier for me to drill out a broken bolt than fool around with extractors.
Next time you have a broken bolt, try this;
Place a flat washer over the broken bolt. Weld the washer to the broken bolt, now weld a nut on top of the washer. Now you can get a tool on the nut.
Before anything cools, work the nut back and forth. Straight pressure will almost certianly pop the nut/washer off the bolt. Work the bolt back and forth until the bolt loosens. A little penetrating oil helps.
Another reason why I don't like spiral fluted eze-outs, you can only apply pressure in one direction.